Conventionally powdered medicine, liquid solvents and an injection device are normally used when powdered injection medicines are given. The powdered medicines are filled aseptically into a vial or an ampule container (referred to as a “carpule” hereinafter). As liquid solvents, distilled water for injection or an isotonic sodium chloride solution are filled aseptically in an ampule or carpule. Typically a syringe is used as the injection device.
It is known in the prior art to provide a syringe having two chambers for use in delivering drugs to medical patients. In particular, dual-chamber syringes are known that allow solid medicine (such as lyophilized material or powder) and liquid solvent (such as water or saline) to be pre-mixed prior to injection into a patient.
U.S. patent application Ser. No. 12/607,498 discloses an improved system to enable the delivery of drugs that come in two forms (i.e. lyophilized matter or powder and liquid solvent) that need to be premixed in an easy, single use, such as when injecting botulinum toxin. The improved system is sterilizable, uses disposable carpules, and allows blood to be aspirated to alert the operator that he/she is mistakenly in a blood vessel. The improved system is a syringe-carpule assembly comprising two carpules, a housing holding the carpules in an end-to-end relationship, an outer hollow plunger rod supported by and slidable relative to the housing, and an inner perforated hollow rod slidably arranged inside the outer hollow plunger rod. The inner perforated hollow rod, when fully extended, has perforations in both carpules, allowing the interior chambers of the carpules to be in fluid communication. Liquid solvent in the rear carpule is then injected into the front carpule, which comprises an evacuated chamber containing solid matter that dissolves in the presence of that solvent to form a mixture. The rear carpule is then removed from the syringe and the mixture in the front carpule is injected into the patient using a needle attached to the end of the syringe housing.
The above-described carpule-syringe assembly is especially useful when the front carpule initially contains only freeze-dried matter, such as lyophilized botulinum toxin. Freeze-drying (also known as lyophilization or cryodesiccation) is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport. The freeze-drying process involves freezing the material and then dehydrating the material by reducing the surrounding pressure to allow the frozen water in the material to sublime directly from the solid phase to the gas phase.
Pharmaceutical manufacturers use lyophilization processes in order to extend the shelf life of certain drugs. In the lyophilization process, a liquid drug contained in a carpule is subjected to a freeze-drying process to extract the aqueous content from the drug, leaving the active components of the drug in a crystalline state in the evacuated and then sealed carpule.
It is known to provide a so-called “lyophilization stopper” comprising a plug with a flange at one end, which plug also has a passage or groove which facilitates extraction of the vaporized aqueous content when the plug is only partially inserted. The lyophilization stopper includes recesses which, when the stopper is partially inserted into a rear opening of an otherwise sealed carpule containing material to be freeze-dried, facilitates fluid communication between the interior of the carpule and the freeze dryer, allowing vapors generated during the lyophilization process to escape from the carpule. After the lyophilization operation, shelves provided within the freeze dryer are typically lowered to contact the stopper and then push it deeper into the carpule to a position whereat the evacuated chamber of the carpule, with its dehydrated contents, is sealed for later use.
There is a need for an improved system to enable the delivery of drugs that come in two forms (i.e. lyophilized matter or powder and liquid solvent) that need to be premixed in an easy, single use, such as when injecting botulinum toxin. Preferably the improved system is sterilizable, uses disposable carpules, and allows blood to be aspirated to alert the operator that he/she is mistakenly in a blood vessel.